[Jaeger] Add HTTP endpoint accepting spans via thrift from Jaeger client

[simitt]

Add HTTP endpoint, running on port 14268 to ingest spans sent by jaeger-client via thrift over http.

Part of #2886

Starting point: implementation from 7.x...axw:otel-7.x

[jalvz]

Verified this works. Started the HotROD sample app from https://www.jaegertracing.io/docs/1.16/getting-started/#sample-app-hotrod and pointed it to apm-server with JAEGER_ENDPOINT environment variable, while having apm-server.jaeger.http.enabled=true.

Jaeger traces show up in the Kibana UI with the equivalent structure of the Jaeger UI. Non default ports work too, and disabling the setting also works as expected.